The broad objectives of this research proposal are to elucidate the ecology, vertebrate host associations, genetic diversity and human disease potential of arenaviruses present in the southwestern United States and northern Mexico. The recent identification of a new arenavirus, Whitewater Arroyo (WWA), infecting rodents in New Mexico and serologic evidence that WWA or related arenaviruses are widely distributed in woodrat (Neotoma spp.) populations throughout the Southwest, raise the real possibility that these agents may be of some public health importance in the region. The specific aims of this project are (l) to determine the geographic distribution and rodent host associations of WWA virus in the Southwestern U.S. and northern Mexico; (2) to study the genetic associations among various woodrat species-and arenaviruses occurring in the same region; (3) to investigate the pathogenesis of WAA virus in its presumed natural rodent host, N albigula; and (4) to determine the prevalence, risk factors and disease associations of infection with WWA and related arenaviruses among humans living in the endemic region. This research is a collaborative effort between scientists at the University of Texas Medical Branch (Galveston) and Texas Tech University (Lubbock). The project is of 3 years duration, consists of both field and laboratory studies, and involves the disciplines of virology, pathology, molecular biology, genetics, mammalogy, ecology and epidemiology.